1. Field of the Invention
The present document relates to a plasma display apparatus and a driving method thereof.
2. Description of the Background Art
FIG. 1 is a view illustrating a discharge shape formed upon a regular glow discharge. An oblique line area shown in FIG. 1 is a bright area emitting a large amount of light. If a DC voltage of a predetermined magnitude or more is applied to a cathode electrode and an anode electrode, an inside of a discharge tube is divided into a cathode glow, a negative glow, a positive column, and an anode glow and emits light.
At this time, because a light emitting amount of visible rays or ultraviolet rays in a negative glow area is larger than that of visible rays or ultraviolet rays generating in a positive column area, negative glow discharge is mainly used in a plasma display panel of a general three electrode surface-discharge structure.
FIG. 2 is a conventional energy recovery circuit diagram and FIG. 3 is a diagram illustrating a sustain pulse waveform formed by a conventional energy recovery circuit. A sustain pulse as in FIG. 3 formed by a conventional energy recovery circuit forms a negative glow discharge of FIG. 1. Therefore, because a moving distance of an electron and art ion is short within a discharge space, light emits only in a section in which a sustain pulse rises and only wall charges are charged without emitting light in the other sections. Therefore, discharge efficiency is not good.
On the other hand, because high brightness and high efficiency of the plasma display panel are continuously required, a method of using a positive column area having discharge efficiency better than negative glow discharge is considered. In the positive column area, because discharge is performed by collision of an electron and an ion accelerated by an electric field which is greatly formed in a cathode dark space, discharge efficiency is good.
However, a distance between a cathode electrode and an anode electrode should be a predetermined value or more to use discharge of a positive column area. That is, as shown in FIG. 1, a positive column area is formed in an anode area while a negative glow area is formed near a cathode electrode.
Therefore, because a space between a scan electrode and a sustain electrode increases to use a positive column area in the plasma display panel, there is a problem that a size of a cell increases.
In addition, there is a problem that a discharge firing voltage increases as a space between electrodes increases. That is, a discharge firing voltage Vf can be expressed as a multiplication function of a pressure P of a discharge gas and a distance d between electrodes depending on a Paschen's law. If the pressure P of the discharge gas is constant, a magnitude of a discharge firing voltage Vf is proportional to a distance d between electrodes. Therefore, if the distance d between electrodes increases to use a positive column area, there is a problem that a discharge firing voltage Vf also increases.